package com.mongodb.rhino.internal;

/**
 * Licence (BSD):
 * <p>
 * ==============
 * <p>
 * Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com)
 * All rights reserved.
 * <p>
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer. Redistributions in binary
 * form must reproduce the above copyright notice, this list of conditions and
 * the following disclaimer in the documentation and/or other materials provided
 * with the distribution. Neither the name of the MiG InfoCom AB nor the names
 * of its contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * <p>
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

import java.util.Arrays;

/**
 * A very fast and memory efficient class to encode and decode to and from
 * BASE64 in full accordance with RFC 2045.<br>
 * <br>
 * On Windows XP sp1 with 1.4.2_04 and later ;), this encoder and decoder is
 * about 10 times faster on small arrays (10 - 1000 bytes) and 2-3 times as fast
 * on larger arrays (10000 - 1000000 bytes) compared to
 * <code>sun.misc.Encoder()/Decoder()</code>.<br>
 * <br>
 * On byte arrays the encoder is about 20% faster than Jakarta Commons Base64
 * Codec for encode and about 50% faster for decoding large arrays. This
 * implementation is about twice as fast on very small arrays (&lt 30 bytes). If
 * source/destination is a <code>String</code> this version is about three times
 * as fast due to the fact that the Commons Codec result has to be recoded to a
 * <code>String</code> from <code>byte[]</code>, which is very expensive.<br>
 * <br>
 * This encode/decode algorithm doesn't create any temporary arrays as many
 * other codecs do, it only allocates the resulting array. This produces less
 * garbage and it is possible to handle arrays twice as large as algorithms that
 * create a temporary array. (E.g. Jakarta Commons Codec). It is unknown whether
 * Sun's <code>sun.misc.Encoder()/Decoder()</code> produce temporary arrays but
 * since performance is quite low it probably does.<br>
 * <br>
 * The encoder produces the same output as the Sun one except that the Sun's
 * encoder appends a trailing line separator if the last character isn't a pad.
 * Unclear why but it only adds to the length and is probably a side effect.
 * Both are in conformance with RFC 2045 though.<br>
 * Commons codec seem to always att a trailing line separator.<br>
 * <br>
 * <b>Note!</b> The encode/decode method pairs (types) come in three versions
 * with the <b>exact</b> same algorithm and thus a lot of code redundancy. This
 * is to not create any temporary arrays for transcoding to/from different
 * format types. The methods not used can simply be commented out.<br>
 * <br>
 * There is also a "fast" version of all decode methods that works the same way
 * as the normal ones, but har a few demands on the decoded input. Normally
 * though, these fast verions should be used if the source if the input is known
 * and it hasn't bee tampered with.<br>
 * <br>
 * If you find the code useful or you find a bug, please send me a note at
 * base64 @ miginfocom . com.
 * 
 * @version 2.2
 * @author Mikael Grev Date: 2004-aug-02 Time: 11:31:11
 */
public class Base64
{
	private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();

	private static final int[] IA = new int[256];
	static
	{
		Arrays.fill( IA, -1 );
		for( int i = 0, iS = CA.length; i < iS; i++ )
			IA[CA[i]] = i;
		IA['='] = 0;
	}

	// ****************************************************************************************
	// * char[] version
	// ****************************************************************************************

	/**
	 * Encodes a raw byte array into a BASE64 <code>char[]</code> representation
	 * i accordance with RFC 2045.
	 * 
	 * @param sArr
	 *        The bytes to convert. If <code>null</code> or length 0 an empty
	 *        array will be returned.
	 * @param lineSep
	 *        Optional "\r\n" after 76 characters, unless end of file.<br>
	 *        No line separator will be in breach of RFC 2045 which specifies
	 *        max 76 per line but will be a little faster.
	 * @return A BASE64 encoded array. Never <code>null</code>.
	 */
	public final static char[] encodeToChar( byte[] sArr, boolean lineSep )
	{
		// Check special case
		int sLen = sArr != null ? sArr.length : 0;
		if( sLen == 0 )
			return new char[0];

		int eLen = ( sLen / 3 ) * 3; // Length of even 24-bits.
		int cCnt = ( ( sLen - 1 ) / 3 + 1 ) << 2; // Returned character count
		int dLen = cCnt + ( lineSep ? ( cCnt - 1 ) / 76 << 1 : 0 ); // Length of
																	// returned
																	// array
		char[] dArr = new char[dLen];

		// Encode even 24-bits
		for( int s = 0, d = 0, cc = 0; s < eLen; )
		{
			// Copy next three bytes into lower 24 bits of int, paying attension
			// to sign.
			int i = ( sArr[s++] & 0xff ) << 16 | ( sArr[s++] & 0xff ) << 8 | ( sArr[s++] & 0xff );

			// Encode the int into four chars
			dArr[d++] = CA[( i >>> 18 ) & 0x3f];
			dArr[d++] = CA[( i >>> 12 ) & 0x3f];
			dArr[d++] = CA[( i >>> 6 ) & 0x3f];
			dArr[d++] = CA[i & 0x3f];

			// Add optional line separator
			if( lineSep && ++cc == 19 && d < dLen - 2 )
			{
				dArr[d++] = '\r';
				dArr[d++] = '\n';
				cc = 0;
			}
		}

		// Pad and encode last bits if source isn't even 24 bits.
		int left = sLen - eLen; // 0 - 2.
		if( left > 0 )
		{
			// Prepare the int
			int i = ( ( sArr[eLen] & 0xff ) << 10 ) | ( left == 2 ? ( ( sArr[sLen - 1] & 0xff ) << 2 ) : 0 );

			// Set last four chars
			dArr[dLen - 4] = CA[i >> 12];
			dArr[dLen - 3] = CA[( i >>> 6 ) & 0x3f];
			dArr[dLen - 2] = left == 2 ? CA[i & 0x3f] : '=';
			dArr[dLen - 1] = '=';
		}
		return dArr;
	}

	/**
	 * Decodes a BASE64 encoded char array. All illegal characters will be
	 * ignored and can handle both arrays with and without line separators.
	 * 
	 * @param sArr
	 *        The source array. <code>null</code> or length 0 will return an
	 *        empty array.
	 * @return The decoded array of bytes. May be of length 0. Will be
	 *         <code>null</code> if the legal characters (including '=') isn't
	 *         divideable by 4. (I.e. definitely corrupted).
	 */
	public final static byte[] decode( char[] sArr )
	{
		// Check special case
		int sLen = sArr != null ? sArr.length : 0;
		if( sLen == 0 )
			return new byte[0];

		// Count illegal characters (including '\r', '\n') to know what size the
		// returned array will be,
		// so we don't have to reallocate & copy it later.
		int sepCnt = 0; // Number of separator characters. (Actually illegal
						// characters, but that's a bonus...)
		for( int i = 0; i < sLen; i++ )
			// If input is "pure" (I.e. no line separators or illegal chars)
			// base64 this loop can be commented out.
			if( IA[sArr[i]] < 0 )
				sepCnt++;

		// Check so that legal chars (including '=') are evenly divideable by 4
		// as specified in RFC 2045.
		if( ( sLen - sepCnt ) % 4 != 0 )
			return null;

		int pad = 0;
		for( int i = sLen; i > 1 && IA[sArr[--i]] <= 0; )
			if( sArr[i] == '=' )
				pad++;

		int len = ( ( sLen - sepCnt ) * 6 >> 3 ) - pad;

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		for( int s = 0, d = 0; d < len; )
		{
			// Assemble three bytes into an int from four "valid" characters.
			int i = 0;
			for( int j = 0; j < 4; j++ )
			{ // j only increased if a valid char was found.
				int c = IA[sArr[s++]];
				if( c >= 0 )
					i |= c << ( 18 - j * 6 );
				else
					j--;
			}
			// Add the bytes
			dArr[d++] = (byte) ( i >> 16 );
			if( d < len )
			{
				dArr[d++] = (byte) ( i >> 8 );
				if( d < len )
					dArr[d++] = (byte) i;
			}
		}
		return dArr;
	}

	/**
	 * Decodes a BASE64 encoded char array that is known to be resonably well
	 * formatted. The method is about twice as fast as {@link #decode(char[])}.
	 * The preconditions are:<br>
	 * + The array must have a line length of 76 chars OR no line separators at
	 * all (one line).<br>
	 * + Line separator must be "\r\n", as specified in RFC 2045 + The array
	 * must not contain illegal characters within the encoded string<br>
	 * + The array CAN have illegal characters at the beginning and end, those
	 * will be dealt with appropriately.<br>
	 * 
	 * @param sArr
	 *        The source array. Length 0 will return an empty array.
	 *        <code>null</code> will throw an exception.
	 * @return The decoded array of bytes. May be of length 0.
	 */
	public final static byte[] decodeFast( char[] sArr )
	{
		// Check special case
		int sLen = sArr.length;
		if( sLen == 0 )
			return new byte[0];

		int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

		// Trim illegal chars from start
		while( sIx < eIx && IA[sArr[sIx]] < 0 )
			sIx++;

		// Trim illegal chars from end
		while( eIx > 0 && IA[sArr[eIx]] < 0 )
			eIx--;

		// get the padding count (=) (0, 1 or 2)
		int pad = sArr[eIx] == '=' ? ( sArr[eIx - 1] == '=' ? 2 : 1 ) : 0; // Count
																			// '='
																			// at
																			// end.
		int cCnt = eIx - sIx + 1; // Content count including possible separators
		int sepCnt = sLen > 76 ? ( sArr[76] == '\r' ? cCnt / 78 : 0 ) << 1 : 0;

		int len = ( ( cCnt - sepCnt ) * 6 >> 3 ) - pad; // The number of decoded
														// bytes
		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		// Decode all but the last 0 - 2 bytes.
		int d = 0;
		for( int cc = 0, eLen = ( len / 3 ) * 3; d < eLen; )
		{
			// Assemble three bytes into an int from four "valid" characters.
			int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

			// Add the bytes
			dArr[d++] = (byte) ( i >> 16 );
			dArr[d++] = (byte) ( i >> 8 );
			dArr[d++] = (byte) i;

			// If line separator, jump over it.
			if( sepCnt > 0 && ++cc == 19 )
			{
				sIx += 2;
				cc = 0;
			}
		}

		if( d < len )
		{
			// Decode last 1-3 bytes (incl '=') into 1-3 bytes
			int i = 0;
			for( int j = 0; sIx <= eIx - pad; j++ )
				i |= IA[sArr[sIx++]] << ( 18 - j * 6 );

			for( int r = 16; d < len; r -= 8 )
				dArr[d++] = (byte) ( i >> r );
		}

		return dArr;
	}

	// ****************************************************************************************
	// * byte[] version
	// ****************************************************************************************

	/**
	 * Encodes a raw byte array into a BASE64 <code>byte[]</code> representation
	 * i accordance with RFC 2045.
	 * 
	 * @param sArr
	 *        The bytes to convert. If <code>null</code> or length 0 an empty
	 *        array will be returned.
	 * @param lineSep
	 *        Optional "\r\n" after 76 characters, unless end of file.<br>
	 *        No line separator will be in breach of RFC 2045 which specifies
	 *        max 76 per line but will be a little faster.
	 * @return A BASE64 encoded array. Never <code>null</code>.
	 */
	public final static byte[] encodeToByte( byte[] sArr, boolean lineSep )
	{
		// Check special case
		int sLen = sArr != null ? sArr.length : 0;
		if( sLen == 0 )
			return new byte[0];

		int eLen = ( sLen / 3 ) * 3; // Length of even 24-bits.
		int cCnt = ( ( sLen - 1 ) / 3 + 1 ) << 2; // Returned character count
		int dLen = cCnt + ( lineSep ? ( cCnt - 1 ) / 76 << 1 : 0 ); // Length of
																	// returned
																	// array
		byte[] dArr = new byte[dLen];

		// Encode even 24-bits
		for( int s = 0, d = 0, cc = 0; s < eLen; )
		{
			// Copy next three bytes into lower 24 bits of int, paying attension
			// to sign.
			int i = ( sArr[s++] & 0xff ) << 16 | ( sArr[s++] & 0xff ) << 8 | ( sArr[s++] & 0xff );

			// Encode the int into four chars
			dArr[d++] = (byte) CA[( i >>> 18 ) & 0x3f];
			dArr[d++] = (byte) CA[( i >>> 12 ) & 0x3f];
			dArr[d++] = (byte) CA[( i >>> 6 ) & 0x3f];
			dArr[d++] = (byte) CA[i & 0x3f];

			// Add optional line separator
			if( lineSep && ++cc == 19 && d < dLen - 2 )
			{
				dArr[d++] = '\r';
				dArr[d++] = '\n';
				cc = 0;
			}
		}

		// Pad and encode last bits if source isn't an even 24 bits.
		int left = sLen - eLen; // 0 - 2.
		if( left > 0 )
		{
			// Prepare the int
			int i = ( ( sArr[eLen] & 0xff ) << 10 ) | ( left == 2 ? ( ( sArr[sLen - 1] & 0xff ) << 2 ) : 0 );

			// Set last four chars
			dArr[dLen - 4] = (byte) CA[i >> 12];
			dArr[dLen - 3] = (byte) CA[( i >>> 6 ) & 0x3f];
			dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';
			dArr[dLen - 1] = '=';
		}
		return dArr;
	}

	/**
	 * Decodes a BASE64 encoded byte array. All illegal characters will be
	 * ignored and can handle both arrays with and without line separators.
	 * 
	 * @param sArr
	 *        The source array. Length 0 will return an empty array.
	 *        <code>null</code> will throw an exception.
	 * @return The decoded array of bytes. May be of length 0. Will be
	 *         <code>null</code> if the legal characters (including '=') isn't
	 *         divideable by 4. (I.e. definitely corrupted).
	 */
	public final static byte[] decode( byte[] sArr )
	{
		// Check special case
		int sLen = sArr.length;

		// Count illegal characters (including '\r', '\n') to know what size the
		// returned array will be,
		// so we don't have to reallocate & copy it later.
		int sepCnt = 0; // Number of separator characters. (Actually illegal
						// characters, but that's a bonus...)
		for( int i = 0; i < sLen; i++ )
			// If input is "pure" (I.e. no line separators or illegal chars)
			// base64 this loop can be commented out.
			if( IA[sArr[i] & 0xff] < 0 )
				sepCnt++;

		// Check so that legal chars (including '=') are evenly divideable by 4
		// as specified in RFC 2045.
		if( ( sLen - sepCnt ) % 4 != 0 )
			return null;

		int pad = 0;
		for( int i = sLen; i > 1 && IA[sArr[--i] & 0xff] <= 0; )
			if( sArr[i] == '=' )
				pad++;

		int len = ( ( sLen - sepCnt ) * 6 >> 3 ) - pad;

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		for( int s = 0, d = 0; d < len; )
		{
			// Assemble three bytes into an int from four "valid" characters.
			int i = 0;
			for( int j = 0; j < 4; j++ )
			{ // j only increased if a valid char was found.
				int c = IA[sArr[s++] & 0xff];
				if( c >= 0 )
					i |= c << ( 18 - j * 6 );
				else
					j--;
			}

			// Add the bytes
			dArr[d++] = (byte) ( i >> 16 );
			if( d < len )
			{
				dArr[d++] = (byte) ( i >> 8 );
				if( d < len )
					dArr[d++] = (byte) i;
			}
		}

		return dArr;
	}

	/**
	 * Decodes a BASE64 encoded byte array that is known to be resonably well
	 * formatted. The method is about twice as fast as {@link #decode(byte[])}.
	 * The preconditions are:<br>
	 * + The array must have a line length of 76 chars OR no line separators at
	 * all (one line).<br>
	 * + Line separator must be "\r\n", as specified in RFC 2045 + The array
	 * must not contain illegal characters within the encoded string<br>
	 * + The array CAN have illegal characters at the beginning and end, those
	 * will be dealt with appropriately.<br>
	 * 
	 * @param sArr
	 *        The source array. Length 0 will return an empty array.
	 *        <code>null</code> will throw an exception.
	 * @return The decoded array of bytes. May be of length 0.
	 */
	public final static byte[] decodeFast( byte[] sArr )
	{
		// Check special case
		int sLen = sArr.length;
		if( sLen == 0 )
			return new byte[0];

		int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

		// Trim illegal chars from start
		while( sIx < eIx && IA[sArr[sIx] & 0xff] < 0 )
			sIx++;

		// Trim illegal chars from end
		while( eIx > 0 && IA[sArr[eIx] & 0xff] < 0 )
			eIx--;

		// get the padding count (=) (0, 1 or 2)
		int pad = sArr[eIx] == '=' ? ( sArr[eIx - 1] == '=' ? 2 : 1 ) : 0; // Count
																			// '='
																			// at
																			// end.
		int cCnt = eIx - sIx + 1; // Content count including possible separators
		int sepCnt = sLen > 76 ? ( sArr[76] == '\r' ? cCnt / 78 : 0 ) << 1 : 0;

		int len = ( ( cCnt - sepCnt ) * 6 >> 3 ) - pad; // The number of decoded
														// bytes
		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		// Decode all but the last 0 - 2 bytes.
		int d = 0;
		for( int cc = 0, eLen = ( len / 3 ) * 3; d < eLen; )
		{
			// Assemble three bytes into an int from four "valid" characters.
			int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

			// Add the bytes
			dArr[d++] = (byte) ( i >> 16 );
			dArr[d++] = (byte) ( i >> 8 );
			dArr[d++] = (byte) i;

			// If line separator, jump over it.
			if( sepCnt > 0 && ++cc == 19 )
			{
				sIx += 2;
				cc = 0;
			}
		}

		if( d < len )
		{
			// Decode last 1-3 bytes (incl '=') into 1-3 bytes
			int i = 0;
			for( int j = 0; sIx <= eIx - pad; j++ )
				i |= IA[sArr[sIx++]] << ( 18 - j * 6 );

			for( int r = 16; d < len; r -= 8 )
				dArr[d++] = (byte) ( i >> r );
		}

		return dArr;
	}

	// ****************************************************************************************
	// * String version
	// ****************************************************************************************

	/**
	 * Encodes a raw byte array into a BASE64 <code>String</code> representation
	 * i accordance with RFC 2045.
	 * 
	 * @param sArr
	 *        The bytes to convert. If <code>null</code> or length 0 an empty
	 *        array will be returned.
	 * @param lineSep
	 *        Optional "\r\n" after 76 characters, unless end of file.<br>
	 *        No line separator will be in breach of RFC 2045 which specifies
	 *        max 76 per line but will be a little faster.
	 * @return A BASE64 encoded array. Never <code>null</code>.
	 */
	public final static String encodeToString( byte[] sArr, boolean lineSep )
	{
		// Reuse char[] since we can't create a String incrementally anyway and
		// StringBuffer/Builder would be slower.
		return new String( encodeToChar( sArr, lineSep ) );
	}

	/**
	 * Decodes a BASE64 encoded <code>String</code>. All illegal characters will
	 * be ignored and can handle both strings with and without line separators.<br>
	 * <b>Note!</b> It can be up to about 2x the speed to call
	 * <code>decode(str.toCharArray())</code> instead. That will create a
	 * temporary array though. This version will use <code>str.charAt(i)</code>
	 * to iterate the string.
	 * 
	 * @param str
	 *        The source string. <code>null</code> or length 0 will return an
	 *        empty array.
	 * @return The decoded array of bytes. May be of length 0. Will be
	 *         <code>null</code> if the legal characters (including '=') isn't
	 *         divideable by 4. (I.e. definitely corrupted).
	 */
	public final static byte[] decode( String str )
	{
		// Check special case
		int sLen = str != null ? str.length() : 0;
		if( sLen == 0 )
			return new byte[0];

		// Count illegal characters (including '\r', '\n') to know what size the
		// returned array will be,
		// so we don't have to reallocate & copy it later.
		int sepCnt = 0; // Number of separator characters. (Actually illegal
						// characters, but that's a bonus...)
		for( int i = 0; i < sLen; i++ )
			// If input is "pure" (I.e. no line separators or illegal chars)
			// base64 this loop can be commented out.
			if( IA[str.charAt( i )] < 0 )
				sepCnt++;

		// Check so that legal chars (including '=') are evenly divideable by 4
		// as specified in RFC 2045.
		if( ( sLen - sepCnt ) % 4 != 0 )
			return null;

		// Count '=' at end
		int pad = 0;
		for( int i = sLen; i > 1 && IA[str.charAt( --i )] <= 0; )
			if( str.charAt( i ) == '=' )
				pad++;

		int len = ( ( sLen - sepCnt ) * 6 >> 3 ) - pad;

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		for( int s = 0, d = 0; d < len; )
		{
			// Assemble three bytes into an int from four "valid" characters.
			int i = 0;
			for( int j = 0; j < 4; j++ )
			{ // j only increased if a valid char was found.
				int c = IA[str.charAt( s++ )];
				if( c >= 0 )
					i |= c << ( 18 - j * 6 );
				else
					j--;
			}
			// Add the bytes
			dArr[d++] = (byte) ( i >> 16 );
			if( d < len )
			{
				dArr[d++] = (byte) ( i >> 8 );
				if( d < len )
					dArr[d++] = (byte) i;
			}
		}
		return dArr;
	}

	/**
	 * Decodes a BASE64 encoded string that is known to be resonably well
	 * formatted. The method is about twice as fast as {@link #decode(String)}.
	 * The preconditions are:<br>
	 * + The array must have a line length of 76 chars OR no line separators at
	 * all (one line).<br>
	 * + Line separator must be "\r\n", as specified in RFC 2045 + The array
	 * must not contain illegal characters within the encoded string<br>
	 * + The array CAN have illegal characters at the beginning and end, those
	 * will be dealt with appropriately.<br>
	 * 
	 * @param s
	 *        The source string. Length 0 will return an empty array.
	 *        <code>null</code> will throw an exception.
	 * @return The decoded array of bytes. May be of length 0.
	 */
	public final static byte[] decodeFast( String s )
	{
		// Check special case
		int sLen = s.length();
		if( sLen == 0 )
			return new byte[0];

		int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

		// Trim illegal chars from start
		while( sIx < eIx && IA[s.charAt( sIx ) & 0xff] < 0 )
			sIx++;

		// Trim illegal chars from end
		while( eIx > 0 && IA[s.charAt( eIx ) & 0xff] < 0 )
			eIx--;

		// get the padding count (=) (0, 1 or 2)
		int pad = s.charAt( eIx ) == '=' ? ( s.charAt( eIx - 1 ) == '=' ? 2 : 1 ) : 0; // Count
																						// '='
																						// at
																						// end.
		int cCnt = eIx - sIx + 1; // Content count including possible separators
		int sepCnt = sLen > 76 ? ( s.charAt( 76 ) == '\r' ? cCnt / 78 : 0 ) << 1 : 0;

		int len = ( ( cCnt - sepCnt ) * 6 >> 3 ) - pad; // The number of decoded
														// bytes
		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		// Decode all but the last 0 - 2 bytes.
		int d = 0;
		for( int cc = 0, eLen = ( len / 3 ) * 3; d < eLen; )
		{
			// Assemble three bytes into an int from four "valid" characters.
			int i = IA[s.charAt( sIx++ )] << 18 | IA[s.charAt( sIx++ )] << 12 | IA[s.charAt( sIx++ )] << 6 | IA[s.charAt( sIx++ )];

			// Add the bytes
			dArr[d++] = (byte) ( i >> 16 );
			dArr[d++] = (byte) ( i >> 8 );
			dArr[d++] = (byte) i;

			// If line separator, jump over it.
			if( sepCnt > 0 && ++cc == 19 )
			{
				sIx += 2;
				cc = 0;
			}
		}

		if( d < len )
		{
			// Decode last 1-3 bytes (incl '=') into 1-3 bytes
			int i = 0;
			for( int j = 0; sIx <= eIx - pad; j++ )
				i |= IA[s.charAt( sIx++ )] << ( 18 - j * 6 );

			for( int r = 16; d < len; r -= 8 )
				dArr[d++] = (byte) ( i >> r );
		}

		return dArr;
	}
}